Converter

[Bigjezza]

Well a little experiment i have a 1/9 scale Abrams i have seen that a henglong TX-7.1 board will work, but i want to use a 24v battery with a coverter 24v to 12v but want to make sure about the wiring any ideas.

[Evan D]

Looks like it would work. I would ohm between the two grounds and maybe the converter chassis to make sure i didn't have a floating ground that could cause grounding loops.

[keilau]

It depends on the voltage of the drive motors of your tank. The Heng Long MFU has built in ESC to drive small motors in the 8 volts range, such as the Mabuchi 300 or 500 series motors. It will not last very long driving higher current 12 volt motor. The key factor is the power rating of the ESC in the Heng Long MFU, not the voltage.

If your tank uses small 8 volt motors, it is much safer to replace the 24V battery with a good quality 8 volt battery such as:

https://www.motionrc.com/products/admiral-7000mah-2s-7-4v-li-ion-battery-with-tamiya-connector-adm6024-015

[Evan D]

Many report running on 3S which is over 12V.

[keilau]

Many report running on 3S which is over 12V.

Do you know what motor @Bigjezza 1/9 scale Abrams uses? The torque of small motor is a function of its rpm. It is much better to use faster motor with internal cooling fan than running the slow motor at higher voltage.

I tried 12V battery myself and do not like it. Both the MFU and the motor run too warm. It is also much better to get brand name motor that has ball bearing on the axle. The ball bearing reduces friction and keeps the motor much cooler.

[Bigjezza]

These are the motors voltage 12v rated current 28amp output 250w

[Evan D]

The ESCs won't handle that.

[Bigjezza]

Any ideas on what i would need to run this beast?

[keilau]

These are the motors voltage 12v rated current 28amp output 250w

The 12V low rpm motor is very popular with robotic hobbyist. You may find some idea at the robotic community.

[tank_me]

I'm confused here. Why are you running 24V battery when everything in your tank is 12V? Why not just run a 12V battery?

You can connect external ESCs to the Heng Long 7.1 which would be my recommendation. In that case, you would connect the PWM cables to the Heng Long MFU and power the ESC directly from a 12V source since your motors are 12V.

Regarding your motors, 2750 is extremely fast for a tank. Are you planning trying to rip the tracks off that Abrams? Maximum RPM I use in my non-realistic paintball battle tanks is 450RPM and that is quite quick. That double chain setup seems like overkill. Looking at this tank it's a bit of a conundrum to me. I see bogie wheels that look like the ones use on the 21st Century Toys Abrams and M5 Stuart, but also looks like it's a metal tub chassis. The tracks look like industrial tabletop chain which I am also familiar with using it on my paintball combat tanks. I use a variation of that motor in my large 1/6th scale tanks, but I use the geared version which puts out closer to 300RPM. I can spin the tracks on my KV-2 paintball tank at 400RPM in grass and the tracks on that vehicle are all steel weighing in at 25lbs per track.

I run a 24V system in my 3D printed M3 Stuart, but it powers my 24V rated ESCs connected to 24V motors. My motorboard (Open Panzer TCB) electronics are stepped down to 9.6V using a buck with an adjustable voltage setting. If you are using a 24V battery and stepping everything down to 12V, all you are doing is dissipating heat through that step down buck. It negates any benefits of running 24V. 24V is more efficient than running 12V as far as current goes. For a hypothetical example, if you are running a motor at 12V it may pull 15A for instance. If you run that same motor at 24V, it may run at say 12A. General numbers to give you an idea - not actually calculated as I would need to gather more info to do that and frankly you need to do that research. In your case though, your motors are 12V so having a 24V battery does nothing. If everything was on 12V, you wouldn't even need that buck converter.

[Bigjezza]

I'm confused here. Why are you running 24V battery when everything in your tank is 12V? Why not just run a 12V battery?

You can connect external ESCs to the Heng Long 7.1 which would be my recommendation. In that case, you would connect the PWM cables to the Heng Long MFU and power the ESC directly from a 12V source since your motors are 12V.

Regarding your motors, 2750 is extremely fast for a tank. Are you planning trying to rip the tracks off that Abrams? Maximum RPM I use in my non-realistic paintball battle tanks is 450RPM and that is quite quick. That double chain setup seems like overkill. Looking at this tank it's a bit of a conundrum to me. I see bogie wheels that look like the ones use on the 21st Century Toys Abrams and M5 Stuart, but also looks like it's a metal tub chassis. The tracks look like industrial tabletop chain which I am also familiar with using it on my paintball combat tanks. I use a variation of that motor in my large 1/6th scale tanks, but I use the geared version which puts out closer to 300RPM. I can spin the tracks on my KV-2 paintball tank at 400RPM in grass and the tracks on that vehicle are all steel weighing in at 25lbs per track.

I run a 24V system in my 3D printed M3 Stuart, but it powers my 24V rated ESCs connected to 24V motors. My motorboard (Open Panzer TCB) electronics are stepped down to 9.6V using a buck with an adjustable voltage setting. If you are using a 24V battery and stepping everything down to 12V, all you are doing is dissipating heat through that step down buck. It negates any benefits of running 24V. 24V is more efficient than running 12V as far as current goes. For a hypothetical example, if you are running a motor at 12V it may pull 15A for instance. If you run that same motor at 24V, it may run at say 12A. General numbers to give you an idea - not actually calculated as I would need to gather more info to do that and frankly you need to do that research. In your case though, your motors are 12V so having a 24V battery does nothing. If everything was on 12V, you wouldn't even need that buck converter.

[Bigjezza]

Yes i have just tried the 12v with the TK-7.1 and it works will be upgraded later, as far as your write up if you don't have something positive to say don't , as i said this was a experiment

[Evan D]

I know it will work with 12V as I said earlier. Then when you said, if I remember right 28A, I said no. The TK will not handle those amps for any length of time.

Yes i have just tried the 12v with the TK-7.1 and it works will be upgraded later, as far as your write up if you don't have something positive to say don't , as i said this was a experiment

[keilau]

I know it will work with 12V as I said earlier. Then when you said, if I remember right 28A, I said no. The TK will not handle those amps for any length of time.

No, the 28A is NOT the operational current. Otherwise, with 2 300Watt plus motors, you can drive a Tesla EV. The 28A is the motor stall rating when the motor can last a fraction of a second before burning up.

None the less, it is not practical to upgrade your tank with Heng Long electronics. You can run it as is. Buy a HL RTR tank and compare them before you decide which one to keep or both.

[Evan D]

Motor says 250W is 0.33 horse power. That will barely power a child's electric bicycle. Either way I wouldn't try to put that X2 through the TK.

No, the 28A is NOT the operational current. Otherwise, with 2 300Watt plus motors, you can drive a Tesla EV. The 28A is the motor stall rating when the motor can last a fraction of a second before burning up.

None the less, it is not practical to upgrade your tank with Heng Long electronics. You can run it as is. Buy a HL RTR tank and compare them before you decide which one to keep or both.

[tank_me]

Yes i have just tried the 12v with the TK-7.1 and it works will be upgraded later, as far as your write up if you don't have something positive to say don't , as i said this was a experiment

I'm guessing this was directed at my comments. Sorry you felt offended, but that's on you. Nothing I said was offensive, as I was trying to help you with limited information. Good luck with the project.

[keilau]

I'm guessing this was directed at my comments. Sorry you felt offended, but that's on you. Nothing I said was offensive, as I was trying to help you with limited information. Good luck with the project.

@tank_me over the year, your extensive knowledge has proven a great help to me. You are always positive.

I read your comment again. Everything is positive and to the point. I do not understand @Bigjezza negative feedback.

[Bigjezza]

Thank you all for help it was a experiment, and it did get hot but worked ESC did not blow, so going to put 2 12v 30 amp motors in and later put in sabertooth dual ESC and open panzer TCB and upgrade when can afford it